Manufacture of fluoro-hydrocarbons



Patented June 30, 1942 UNITED STATES PATENT- OFFICE Q MANUFACTURE g-nmnocm- Q I.

Mam v. Grosse and Carl. B. Linn, Chicago,

assignors to Universa Chicago,

1 Oil Products Company, Ill., a corporation of Delaware.

I No Drawing. Application October 31 1938, Serial No. 238,051 I J '1Claims. (01. 260-653) This invention relates particularly to themanufacture of compounds having the general formula, RCF2-R' in which Rmay be an alkyl radical such as CH3, CzHs, etc., R may be a hydrogenatom or an alkyl radical, and the other letters have the values commonlyassigned to them as representing chemical elements.

The invention is more specifically concerned with the manufacture of theabove compounds under particular conditions in respect to temperaturecontrol so that side reactions are minimized and practical yields of thedesired products are obtained.

Compounds of the above general formulaare known as di-fluoro-paraflinsand are completely stable in that they do not split oil? hydrogenfluoride on standing under ordinary temperature and pressure conditionsor during distillation as do some alkyl fluorides, especially tertiaryfluorides. The compounds have generally a pleasant odor and areutilizable as refrigerating liquids.

In one specific embodiment the present invention comprises themanufacture of di-iluoroparaflins by reacting hydrocarbons of theacetylene series of-higher molecular weight thanacetylene with liquidanhydrous hydrogen fluo- The operations by which the compounds of theinvention are prepared are relatively simple. In batch or intermittentprocesses, hydrogen fluorideis liquefied and brought to the proper re-,action temperature in a vessel surrounded by a heat-absorbing bath,such as, for example, a

mixture of acetone and carbon dioxide, in case 1 operations areconducted at low temperatures of the order of C. or lower. While thedesired the abstraction of the heat of reaction so that the temperatureis not allowed to rise above a fixed point. As will be shown in laternumerical examples, it is necessary to maintain a considerable excess of.hydrogen fluoride at all times to eliminate the tendency'oftheacetylene hydroreactions will take place to produce substantial Iyields of di-fluoro paraflins at temperatures up to the normal boilingpoint of hydrogen fluoride, to wit, 0., low temperatures favor morecarbons to polymerize and insure the direct addition of hydrogenfluoride as a predominating reaction. When the proper amount ofacetylene hydrocarbon has been introduced and there is still .an excessof liquid hydrogen fluoride, operations are stopped and the upper layerof fluo ride is withdrawn. Obviously the operation may be madecontinuous by providing means for the controlled addition of both theacetylene hydrocarbon and the hydrogen fluoride at, one point in areaction vessel and separation of the two a layers at another pointwithithe return of'unconverted hydrogen fluoride. The products" of thereaction are washed with alkaline materialsand dried withcalcium..chloride and distilled for a final purification."

The typical reaction involved in the presentinstance isshown by thefollowing equation:

R-CECIR+2HF R-gcmu' The reaction is characteristic of all compounds ofthe acetylene series except acetylene itself up to the point wheredifiiculties are encountered by v the solidificationof the highermolecular weight members of the series or the iluorinated products atthe necessary temperatures of the reaction, and under thesecircumstances, the use of hydrocarbon solvents may be resorted to.

The following numerical data is given to illustrate the scope of theinvention, but it is not intended that the invention bein any waylimited thereby.

A number of runs were conducted on different hydrocarbons, the resultsof which are summarized in the following table:

Propyne Hexyne-l Hcxyno-3 Hcptyne-l Alkfiie charged:

ols 0.47 0.212 0. 361 0.297 Grams 19 17.4 29.6 -28. 5 Temp. reaction 0..66 to -7lto tr 40 to 70 Time of addition of hydrocarbon ;minutes 70 7065 Hydrogen fluoride charged:

Mols 4. 30 2.17 3. 57 4, 85 Gram; 86. 0 43. 4 71. 5 97.1 Crude, waterinsoluble roduct recovercdgmms. 23. 3 22.1 39. 4 34. 5 Concentration ofpure i-fluoride in crude product as shown by distillation .wt. percent"79 35 60 Yield di-fluoride based on alkyne charge pcrcont. 61 68 76 52selective reactions over those resulting from Mt polymerization. Inpractical operations, copper linedsvessels have been found to give thebest service. The acetylene hydrocarbon is then slowly introduced belowthe surface of the lique-' fied hydrogen fluoride at a rate whichpermits co In all cases there was some production of amorphous solidmaterials produced by the polymerization of the acetylene hydrocarbons,but these were heavy and readily separable from the desired reactantproducts. e

The following tabulation shows a comparison of the properties of theproducts as reported previously in the chemical literature'and asproduced, and shows that the products of the reaction were hexanes-whichcomprises gradually introducing hexynes into substantially anhydrousliquid hydrogen fluoride at a temperature ,below C.,

parafflns which comprises interacting a member of the acetylene seriesof higher molecular weight than acetylene with a molal excess ofsubstantially anhydrous liquid hydrogen fluoride at a temperature belowthe boiling point of hydrogen fluoride.

2. A process for the manufacture of di-fluoroparaflins which comprisesgradually introducing a liquefied member of the acetylene series ofhydrocarbons of higher molecular weight than acet-' ylene intosubstantially anhydrous liquid hydrogen fluoride at a temperature belowthe boiling e, while abstracting heat ubstantial temperature point ofhydrogen fiuorid of reaction to prevent s rise, and maintaining a molalexcess of hydro fluoride.

3. A process for the manufacture of 2,2'-difluoro-propane whichcomprises gradually introducing propyne into substantially anhydrousliquid hydrogen fluoride at atemperature below 0 C., while abstractingheat of reaction to prevent substantial temperature rise, andmaintaining a molal excess of hydrogen fluoride.

gen

4. A process for the manufacture of di-fluorosubstantially pure. whileabstracting heat of reaction to prevent sub- Propyne Hexyne-l Hexyne'tlHeptyne-l Reactants, HF+

Product 2, Z-di-fluoro propane 2, Z-di-fluoro hexane 3, a-di-fluorohexane 2, 2-di-fluoro heptane Report. Prod. Report. Prod. Report. Prod.Report. Prod.

Properties:

Percent H 7. 56 7. 54 9. 46 9. 91 10.32 44. 97 45. 00 56. 42 58. 97 61.51 47. 47 47. 00 34. 12 31. 12 v 28. 17 80. 77 122 122. 134 mm 0. 5l755mm. 86. ll750 mm. 86 0l742 mm 111. 1I740 mm. 1.3118 1. 353B 1. 35 1.3651 42. 5 +20. 0 +20. 0 +21. 5 1. 03 at ---80 8918 .8880 104.8

We claim as our invention: stantial temperature rise, and maintaining al. A process for the manufacture of difiuoromolal excess of hydrogenfluoride.

5. A process for the manufacture of cli-fluoroheptanes which comprisesgradually introducing heptynes into substantially anhydrous liquidhydrogen fluoride at a temperature below 0 C., while abstracting heat ofreaction to prevent substantial temperature rise, and maintaining amolal excess of hydrogen fluoride.

6. A process for producing difluoro-paraiilns which comprises reacting ahydrocarbon'of the acetylene series and of higher molecular weight thanacetylene with substantially anhydrous liquid hydrogen fluoride at. atemperature not appreciably in excess of 0 C. while imaintaining a molalexcess of hydrogen fluoride.

7. A process for producing difluoro which comprises introducing to a ahydrocarbon of the acetylene series an -parafiins molal excess ofsubstantially anhydrous liquid hydrogen fluoride, reacting saidhydrocarbon with hydrogen fluoride in the reaction zone, and abstractingsufiicient heat from'said zone to maint'ain thereina reactiontemperature below 0 C.

' ARISTID V. GROSSE.

CARL B. LINN.

reaction zone. d of higher molecular weight than acetylene and a

